vulnerability / NVI-00017664 / Revision 1
Flask-Security has an Open Redirect issue
GitHub lists this reviewed advisory for Flask-Security. Published version ranges and source prerequisites are shown below; this is not an inspection of a visitor’s application.
This report has not inspected your inventory, configuration, deployed build, reachability or evidence. A catalog listing and a severity score do not establish exposure or compromise.
01 / Meaning
Why it matters
Published affected context helps an owner decide what evidence to gather. This report has not examined your application.
4.7 medium
GitHub source severity; exploitability and local consequence require separate evidence.
As of · GitHub Advisory Database
02 / Applicability
The affected context
Affected versions, configuration prerequisites and known exclusions are public. Confirm each one against the deployed service.
Flask-Security
source listed<= 5.8.0
# Open Redirect in Flask-Security ## Summary `flask_security.utils.validate_redirect_url()` can allow an attacker-controlled redirect URL when subdomain redirects are enabled. The bypass uses a backslash inside the URL authority/host: ```text http://evil.com\.whitelist.com http://evil.com%5C.whitelist.com ``` Python's `urlsplit()` parses the full authority as `evil.com\.whitelist.com` or `evil.com%5C.whitelist.com`. Because the value ends with `.whitelist.com`, `validate_redirect_url()` accepts it as an allowed subdomain of `whitelist.com`. This is similar in class to the previous Flask-Security-Too open redirect advisory CVE-2023-49438 / GHSA-672h-6x89-76m5, where crafted redirect URLs bypassed validation through browser URL normalization behavior. ## Affected Configuration The issue requires subdomain redirects to be enabled: ```python SERVER_NAME = "whitelist.com" SECURITY_REDIRECT_ALLOW_SUBDOMAINS = True ``` Tested environment: ```text Flask-Security: 5.8.0 Flask: 3.1.3 Werkzeug: 3.1.8 ``` ## Impact An attacker can craft a URL that passes Flask-Security's redirect validation and produces a `302` response to an attacker-controlled URL-like authority. This can be us
03 / Response
What to do next
- investigate
Identify the exact component and deployed version, examine the linked publisher’s conditions, and retain evidence of any mitigation.
Confirm current vendor support, compatibility and deployment evidence. This report has not tested a fix in your system. GitHub Advisory Database
A fixed release is not deployment evidence.
Check current vendor support and compatibility. After making a change, verify the deployed build and relevant runtime conditions. Keep the evidence, owner and time. An updated lockfile alone does not prove what is running.
04 / Limits
What this report cannot establish
- Customer inventory, deployment, reachability and exploitation have not been inspected.
05 / Provenance
Sources you can inspect
Each assertion retains its source. Mirrored records may repeat one underlying publisher; additional links are not independent corroboration.
- GHSA-w2j7-f3c6-g8cw ↗
GitHub Advisory Database · vendor advisory
Observed . GitHub Advisory Database; CC-BY-4.0. Each advisory links its original attribution. Null normalizes fields.
Public revision history
Only published revisions appear here. Routine fetches do not create a material-change event.
- Revision 1 ·
First indexed by Null; source disclosure date is shown separately.